Well we are far the creation of the Wehrmacht Myth of Invincibility and the realty of its deep involvement in the extermination process…

To counter the parallel between the US Japanese camps:
Can you find Jewish SS division? That is because you can find Japanese origin US battalion.

“When you're cornered, you act even more vilely. The "final solution" came to be pursued harder after Stalingrad, Kursk and the assault on Sicily”
Nope. The use of brutality was in the heart of the Nazi political system and they input it in the Werhmacht’s doctrine. Shock and terror as we say today but with more brutality and more plnned horror than it can be imagine.
The killing of English and French prisoners happened when the Germans Army was victorious… The early killings in Russia and the extermination of entire Jewish populations started immediately after the crossing of the borders.
The 20th of January 1942, during the Wannsee Conference the Nazi organised the technical aspect of massive deportation and extermination of all sub-humans but the decision was long time ago decided. And at that time the Germans were entitled to think they would win the war. The lost of Stalingrad (the Army of) was of course a disaster but the Germans were confident they would recovered, and de facto, they did, as you have to wait Kursk to see the first German summer offensive failure.

“One counter-example, a strong one, would be Stalin's frenzy following his victory.” Stalin? Did he built extermination camp or deport Germans to death camps. He did it for political opponents and “traitors” but not for the Germans. He treated the Polish worst than the Germans, IMO.